1. Field of the Invention
This invention generally relates to communications structured in a digital wrapper and, more particularly, to a system and method for programming the frame synchronization criteria in the communication frame structure.
2. Description of the Related Art
Frame synchronization is used in most communication technologies where extra bandwidth is required to add functionality into the original data stream. There is no standard practice with respect to the bandwidth allocation of frame synchronization words. Neither is there an ability to customize the use of that bandwidth for synchronization thresholding adaptive to various bit error rate conditions in a variable rate forward error correction (FEC) system implementing an interleaved multi-frame superframe.
It would increase information bandwidth if all the bytes, or words of a digital frame structure could be devoted to payload. However a significant portion of the frame is devoted to FEC to remove errors that are introduced in data transmission lines. Even fiber optic systems can be noisy enough to introduce errors, when the distance between nodes is great enough. Part of the frame must also be used for maintenance functions between communication nodes. Further, a portion of the frame must be devoted to synchronization. The synchronization function becomes even more critical when the frames are scrambled to randomize the data density. These maintenance and synchronization bytes reside in the overhead section of the frame. However, as mentioned above, there is no standard protocol defining the number, location, or value of frame synchronization bytes. Hardware devoted to any particular protocol or implementation quickly becomes obsolete. An exclusively software approach to managing communications is cumbersome.
It would be advantageous if communication hardware could be developed that permitted flexibility in defining the frame synchronization byte structure, so as to permit the hardware to be used in a number of communication standards.
It would be advantageous if the number of frames, with recognizable frame synchronization bytes (FSBs), required for synchronization could be made selectable in a multidimensional digital frame structure.
Likewise, it would be advantageous if the quantity, location, values, and bit error rates of the FSBs could be made selectable to accommodate a number of communication standards, or changes to existing standards.